Re: [BUG] blocked task after exynos_drm_init

From: Andrzej Hajda <a.hajda@samsung.com>
To: Krzysztof Kozlowski <k.kozlowski@samsung.com>,
	Inki Dae <inki.dae@samsung.com>,
	Joonyoung Shim <jy0922.shim@samsung.com>,
	Seung-Woo Kim <sw0312.kim@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>
Cc: linux-samsung-soc@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [BUG] blocked task after exynos_drm_init
Date: Tue, 18 Nov 2014 11:42:22 +0100	[thread overview]
Message-ID: <546B228E.6030500@samsung.com> (raw)
In-Reply-To: <1415264811.27478.4.camel@AMDC1943>

On 11/06/2014 10:06 AM, Krzysztof Kozlowski wrote:
> Hi,
> 
> On last next (next-20141104, next-20141105) booting locks after
> initializing Exynos DRM (Trats2 board):
> 
> [    2.028283] [drm] Initialized drm 1.1.0 20060810
> [  240.505795] INFO: task swapper/0:1 blocked for more than 120 seconds.
> [  240.510825]       Not tainted 3.18.0-rc3-next-20141105 #794
> [  240.516418] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [  240.524173] swapper/0       D c052534c     0     1      0 0x00000000
> [  240.530527] [<c052534c>] (__schedule) from [<c0525b34>] (schedule_preempt_disabled+0x14/0x20)
> [  240.539030] [<c0525b34>] (schedule_preempt_disabled) from [<c0526d44>] (mutex_lock_nested+0x1c4/0x464)
> [  240.548320] [<c0526d44>] (mutex_lock_nested) from [<c02be908>] (__driver_attach+0x48/0x98)
> [  240.556562] [<c02be908>] (__driver_attach) from [<c02bcc00>] (bus_for_each_dev+0x54/0x88)
> [  240.564717] [<c02bcc00>] (bus_for_each_dev) from [<c02bdce0>] (bus_add_driver+0xe4/0x200)
> [  240.572876] [<c02bdce0>] (bus_add_driver) from [<c02bef94>] (driver_register+0x78/0xf4)
> [  240.580864] [<c02bef94>] (driver_register) from [<c029e99c>] (exynos_drm_platform_probe+0x34/0x234)
> [  240.589890] [<c029e99c>] (exynos_drm_platform_probe) from [<c02bfcf0>] (platform_drv_probe+0x48/0xa4)
> [  240.599090] [<c02bfcf0>] (platform_drv_probe) from [<c02be680>] (driver_probe_device+0x13c/0x37c)
> [  240.607940] [<c02be680>] (driver_probe_device) from [<c02be954>] (__driver_attach+0x94/0x98)
> [  240.616360] [<c02be954>] (__driver_attach) from [<c02bcc00>] (bus_for_each_dev+0x54/0x88)
> [  240.624517] [<c02bcc00>] (bus_for_each_dev) from [<c02bdce0>] (bus_add_driver+0xe4/0x200)
> [  240.632679] [<c02bdce0>] (bus_add_driver) from [<c02bef94>] (driver_register+0x78/0xf4)
> [  240.640667] [<c02bef94>] (driver_register) from [<c029e938>] (exynos_drm_init+0x70/0xa0)
> [  240.648739] [<c029e938>] (exynos_drm_init) from [<c00089b0>] (do_one_initcall+0xac/0x1f0)
> [  240.656914] [<c00089b0>] (do_one_initcall) from [<c074bd90>] (kernel_init_freeable+0x10c/0x1d8)
> [  240.665591] [<c074bd90>] (kernel_init_freeable) from [<c051eabc>] (kernel_init+0x8/0xec)
> [  240.673661] [<c051eabc>] (kernel_init) from [<c000f268>] (ret_from_fork+0x14/0x2c)
> [  240.681196] 3 locks held by swapper/0/1:
> [  240.685091]  #0:  (&dev->mutex){......}, at: [<c02be908>] __driver_attach+0x48/0x98
> [  240.692732]  #1:  (&dev->mutex){......}, at: [<c02be918>] __driver_attach+0x58/0x98
> [  240.700367]  #2:  (&dev->mutex){......}, at: [<c02be908>] __driver_attach+0x48/0x98

This is caused by patch moving platform devices to
/sys/devices/platform[1]. Since this patch registering platform
drivers/devices in probe of platform device causes deadlocks. I guess
now all driver registration should be moved to exynos_drm_init and it
seems better location for it IMHO.

Regards
Andrzej

[1]: http://www.spinics.net/lists/devicetree/msg56101.html

> 
> Full dmesg and config attached.
> 
> Best regards,
> Krzysztof
> 
> 
> 
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